Cognitive Issues

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Cognitive Issues Human Tasks

• CS 7450 - Information Visualization
• January 18, 2005
• John Stasko

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Outline

• Overview
• 1. Role How visualizations aid cognition?
• 2. Tasks What does the visualization assist?

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Basic Premise

• Understanding (the cognitive aspects) is the
  crucial part of InfoVis
• Visualization is simply a tool useful for aiding
  comprehension and understanding
• Discussed the role of external cognition aids
  briefly last time

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How Are Graphics Used?

• What does a visualization or graphic image
  provide for us?

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How Are Graphics Used?

• Larkin Simon 87 investigated usefulness of
  graphical displays
• Graphical visualization could support more
  efficient task performance by
• Allowing substitution of rapid perceptual
  influences for difficult logical inferences
• Reducing search for information required for task
  completion
• Sometimes text is better

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Cognitive Map

• What is it?

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Understanding

• People utilize an internal model that is
  generated based on what is observed
• Tversky calls the internal model a cognitive map
• Think about that term

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Example

• Youre taking the MARTA train to get to Georgia
  State University
• You have some existing internal model of the
  system, stops, how to get there
• On train, you glance at MARTA map for help
• Refines your internal model, clarifying items and
  extending it
• Note that its still not perfect, no internal
  model ever is

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Cognitive Map

• Just dont have one big one
• Have large number of these for all different
  kinds of things
• Collection of cognitive maps --gt Cognitive collage

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1. Process Models

• (Recall the user and cognitive models from HCI?)
• Process by which a person looks at a graphic and
  makes some use of it
• A number of substeps probably exist
• Can you describe process?

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Process Model 1

• Spence
• Navigation - Creation and interpretation of an
  internal mental model

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Navigation
Content
Model
Browse
Browsingstrategy
Internalmodel
Formulate abrowsingstrategy
Interpret
Interpretation
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Interpretation

• Can someone explain that?

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Interpretation

• Content is the display on screen. Modeling of
  that pattern results in cognitive map.
  Interpretation (ah, variables x and y are
  related) leads to new view, that generates an
  idea for a new browsing strategy. Look at the
  display again with that.

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Process Model 2

• Card, Mackinlay, Shneiderman book
• Knowledge crystallization task
• Gather info for some purpose, make sense of it by
  constructing a representational framework, and
  package it into a form for communication or action

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Knowledge Crystallization

• Information foraging
• Search for schema (representation)
• Instantiate schema
• Problem solve to trade off features
• Search for a new schema that reduces problem to a
  simple trade-off
• Package the patterns found in some output product

From CMS 98
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How Vis Amplifies Cognition

• Increasing memory and processing resources
  available
• Reducing search for information
• Enhancing the recognition of patterns
• Enabling perceptual inference operations
• Using perceptual attention mechanisms for
  monitoring
• Encoding info in a manipulable medium

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Process
task
Raw data
Data tables
Visual Structures
Views
Data transformations
Visual mappings
View transformations
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Knowledge Crystallization
Overview Zoom Filter Details-on-demand Browse Sear
ch query
Task
ExtractCompose
Author,decideor act
Foragefor data
Search forschema
Problem-solve
Reorder Cluster Class Average Promote Detect
pattern Abstract
Instantiateschema
Read fact Read comparison Read pattern Manipulate
Create Delete
Instantiate
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Intermission

• Popcorn sodas for everyone!
• Admin stuff
• Circulate photos
• Anyone need an info form yet?

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2. User Tasks

• What things will people want to accomplish using
  information visualizations?
• Last time, we discussed
• search vs. browsing

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Browsing vs. Search

• Important difference in activities
• Appears that information visualization may have
  more to offer to browsing
• Butbrowsing is a softer, fuzzier activity
• So, how do we articulate utility?
• Maybe describe when its useful
• When is browsing useful?

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Browsing

• Useful when
• Good underlying structure so that items close to
  one another can be inferred to be similar
• Users are unfamiliar with collection contents
• Users have limited understanding of how system is
  organized and prefer less cognitively loaded
  method of exploration
• Users have difficulty verbalizing underlying
  information need
• Information is easier to recognize than describe

Lin 97
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Thought

• Maybe infovis isnt about answering questions or
  solving problems hmmm
• Maybe its about asking better questions

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Tasks

• OK, but browsing and search are very high level
• Lets be more specific

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Example from Last Time
Which state has the highest income? Is there a
relationship between income and education? Are
there any outliers?
Questions
Example courtesyof Chris North
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Exercise

• What are the (types of) tasks being done here?
• Can you think of others?
• Lets develop a list

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Task Taxonomies

• Number of different ones exist, important to
  understand what process they focus on
• Creating an artifact
• Human tasks
• Tasks using visualization system
• ...

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Shneiderman

• Whats his mantra?
• Overview first, then zoom filter, then details
  on demand
• Overview first, then zoom filter, then details
  on demand
• Overview first, then zoom filter, then details
  on demand
• Overview first, then zoom filter, then details
  on demand

VL 96
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Elaborated More

• Task set?
• Overview
• Zoom
• Filter
• Details on demand
• Relate
• History
• Extract
• Are these end-user tasks?

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User Tasks

• Wehrend Lewis created a low-level, domain
  independent taxonomy of user tasks in
  visualization environments
• Eleven basic actions
• identify, locate, distinguish, categorize,
  cluster, distribution, rank, compare within
  relations, compare between relations, associate,
  correlate

Vis 90
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WL 1

• Locate
• Finding something that one knows about already

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WL 2

• Identify
• Describe an object not necessarily known
  previously

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WL 3

• Distinguish
• Detecting different values of same variable

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WL 4

• Categorize
• Define divisions that visual objects can be
  sorted by

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WL 5

• Cluster
• Determining whether data items are clustered or
  not

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WL 6

• Distribution
• Describe overall pattern of data

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WL 7

• Rank
• Finding best and worst, for example

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WL 8

• Compare within entities
• Decide something based on attributes of similar
  objects

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WL 9

• Compare between relations
• Different or sets of entities used as basis of
  comparison

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WL 10

• Associate
• Form relationship between objects on display

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WL 11

• Correlate
• Determine which objects share similar attributes

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Another Taxonomy

• Zhou and Feiner
• More for multimedia explanation than for
  infovis, but still useful to us

CHI 98
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Visual Task Taxonomy

• Zhou and Feiner developed a hierarchical
  taxonomy/model of visual tasks

Correlate -- Plot -- MarkCompose Distinguish --
MarkDistribue -- Isolate Emphasize -- Focus --
Isolate -- Reinforce Generalize --
Merge Identify -- Name -- Portray --
Individualize -- Profile
Locate -- Position -- Situate -- Pinpoint --
Outline Rank -- Time Reveal -- Expose --
Itemize -- Specify -- Separate Switch
Direct visual organizing and encoding
tasks Encode -- Label -- Symbolize -- --
Quantify -- -- Iconify -- Portray -- Tabulate --
Plot -- Structure -- Trace -- Map
Relational tasks Associate -- Collocate --
Connect -- Unite -- Attach Background Categorize -
- MarkDistribute Cluster -- Outline --
Individualize Compare -- Differentiate --
Intersect
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Interpretation

• The nested items are refinements of particular
  ways of achieving task
• E.g., To locate an item, we might use the more
  specific visual task pinpoint

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Dimensions

• Visual tasks have two main dimensions
• 1. Visual accomplishments - describe presentation
  intents that task might help to achieve
• 2. Visual implications - particular type of
  visual action that visual task may carry out

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1. Visual Accomplishments

• All about presentation intent
• Classified into two categories
• Tasks that inform the user (e.g., make a
  presentation with ppt)
• Tasks that enable user to explore or compute
  (e.g., decide which stock to buy)
• Each of these can be broken down further

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Visual Accomplishments
Inform
Enable
Elaborate Summarize Explore
Compute
Associate Background Categorize Cluster Compare Co
rrelate Distinguish Generalize Identify Locate Ran
k
Emphasize Reveal
Search Verify Sum Differentiate
Correlate Locate Rank
Correlate Locate Rank
Categorize Cluster Compare Correlate Distinguish E
mphasize Identify Locate Rank Reveal
Categorize Compare Correlate Distinguish Identify
Locate Rank Reveal
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2. Visual Implications

• Categorize various visual tasks by whether they
  imply
• Certain types of visual organization
• Certain ways of visual signaling
• Certain paths of visual transformation

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Making InfoVis More Task-Focused

• InfoVis
• Representational Primacy
• Show the data truthfully in meaningful ways
• Analytic Primacy
• Support user analysis and tasks

Amar Stasko InfoVis 04
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User Tasks

• Examples of higher-level tasks
• Complex decision making, especially under
  uncertainty
• Learning a domain
• Identifying the nature of trends
• Predicting the future

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Closing the Gaps
Narrowing the gaps between representation and
analysis
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Narrowing Methods

• Knowledge Precepts (for design and evaluation)
• Worldview Gap
• 1. Determine domain parameters
• 2. Expose multivariate explanation
• 3. Facilitate hypothesis testing
• Rationale Gap
• 1. Expose uncertainty
• 2. Concretize relationships
• 3. Expose cause and effect

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Visual Analytics

• Formation of abstract visual metaphors in
  combination with human information discourse
  (interaction) that enables detection of the
  expected and discovery of the unexpected within
  massive, dynamically changing information spaces
• Intelligence analysis
• Bioinformatics
• Financial analysis

Wong ThomasIEEE CGA, 04
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NVAC

• National Center formed by Dept. of Homeland
  Security to assist with intelligence analysis,
  emergency response, border patrol, etc.
• Blending cognitive analyses, hypothesis testing
  with visualization to develop better techniques
  and systems

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HW 1

• Example due Thursday

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HW 2

• Turn in today
• Challenging?

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HW 3

• Given set of incomplete, missing and inconsistent
  facts
• Develop hypothesis for what is planned to occur
• Turn-in
• Hypothesis (paragraph)
• The visual aids you created, if any
• Due next Tuesday

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Odds-n-Ends

• Co-web
• Office hours
• Logo

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Upcoming

• Multivariate Data
• The DB session
• Reading
• Chapter 3
• Inselberg paper
• Multivariate visualization tools
• Graphical principles

Be reading Tufte
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References

• Spence CMS texts
• All referred to papers